Electromechanical transducer and method of manufacturing the same

Abstract

An electromechanical transducer includes: a conductive substrate; multiple elements which are disposed on a first face side of the substrate and which contain cells; grooves; and insulating films. The substrate has a second face which is opposite from the first face. The grooves run from the second face of the substrate to the first face of the substrate in a manner that electrically isolate the multiple elements from one another, thereby dividing the substrate and forming first electrodes. The insulating films are formed on opposing outer side walls of every two adjacent first electrodes across one of the grooves. The width between the insulating films is narrower on the second face side of the substrate than on the first face side of the substrate. The insulating films are thicker on the second face side than on the first face side.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an electromechanical transducer such as an ultrasonic transducer, and to a method of manufacturing the electromechanical transducer. More specifically, the present invention relates to a technology of improving the reliability of an electromechanical transducer.[0003]2. Description of the Related Art[0004]Ultrasonic transducers perform conversion from an electrical signal to an ultrasonic wave and conversion from an ultrasonic wave to an electrical signal, and are used, among others, as probes for medical imaging or non-destructive inspection. One form of ultrasonic transducer is a capacitive micromachined ultrasound transducer (CMUT). A CMUT generally includes a substrate, which has a lower electrode, a membrane, which is supported to the substrate by a supporting portion formed on the substrate, and an upper electrode. The CMUT uses a voltage applied between the lower electrode and the...

AI Technical Summary

Benefits of technology

[0009]According to the present invention, where the outer side walls of the first electrodes separated from one another by the grooves are covered with the insulating films, a foreign object entering one of the grooves which are gaps is prevented from causing a short circuit between the first electrodes adjoined to the groove. In addition, the width between the insulating films on the opposing outer side walls of every two adjacent first electrodes is narrower on the groove opening side (i.e., the side of the second face of the substrate which is opposite from the first face of the substrate) than on the groove bottom side (i.e., the side of the first face of the substrate). This means that a foreign object that manages to enter the groove is smaller than the width of a deeper part of the groove away from the opening (the groove bottom width), and does not span the distance between the opposing outer side walls of the adjacent first electrodes. Consequently, a higher inter-electrode insulation effect is expected and the electromechanical transducer is improved in reliability.

Problems solved by technology

However, with a conventional CMUT that has a groove for separating one lower electrode from another as described above, there is a possibility of a conductive foreign object entering the groove during the manufacture process or while the CMUT is in use, and bridging the lower electrodes adjoined to the groove to cause a short circuit.

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